Aqueous gel explosives which derive their chemical energy mainly from thermal decomposition of ammonium nitrate are used extensively in quarrying, excavating and mining, primarily because they are cheap and safe to handle. These explosives usually contain expensive suspended solid fuels and cannot be detonated with blasting caps, but require substantial high explosive booster charges to obtain efficient detonation. There are needed both cheaper non-cap sensitive explosives containing no solid fuels or sensitizers and also explosives that can be placed and detonated in a manner similar to dynamite, but which are cheaper and much less prone to accidental detonation. We have discovered that a class of aqueous gel explosives based on ammonium nitrate suspensions can readily be made without the use of suspended solid fuels and can also be converted to cap sensitive form, in which they will serve as relatively safe substitutes for dynamite.
Gelled aqueous ammonium nitrate suspension explosives are known. In U.S. Pat. No. 3,676,236 of Klima et al there are disclosed explosive compositions made up of varying proportions of ammonium nitrate, sodium nitrate, ammonium perchlorate, hexamethylenetetramine, nitric acid, a finely divided solid fuel, a hydroxy-substituted thickening agent and a cross-linking agent. The prior art explosive compositions are particularly useful for placement in rather large, widely spaced drill holes such as are customarily found in open pit hard rock mining. Explosives of this type are customarily detonated by means of blasting caps and high explosive booster charges.